1. Field of the Invention
The present invention relates generally to vapor deposition metallizing apparatus and it relates more particularly to an apparatus and process for continuously transporting components to be metallized through a series of vacuum chambers.
2. Description of the Prior Art
Many articles of manufacture must be coated with metal for various reasons. One such article is a retroreflective highway marker comprising a metal coated lens having retroreflective cells. Typically, these lenses have lenses which are plastic. One method of coating the markers with a thin layer of metal, such as aluminum, is by the process of batch vapor deposition. In this process, the lenses are mounted to a carrier and masked to expose the surfaces to be metallized. The carrier is then placed in a large vacuum chamber wherein the air within the chamber is withdrawn to a vacuum on the order of 10.sup.-5 torr. A plurality of electric filaments having pieces of aluminum placed within them are energized such that the aluminum vaporizes and fills the chamber. The vapor is thereby deposited on the exposed surfaces of the lenses. The chamber is then brought back up to atmospheric pressure such that the chamber door can be opened and the carrier with metallized components can be removed. By this process a coating of metal on the order of 10,000 angstroms can be deposited on the components. Such a coating is sufficient to give a retroreflective lens a light reflective layer, of metal.
A disadvantage of known metallizing apparatus and processes is that a batch-type arrangement is time consuming to set up and implement. A single, large chamber requires considerable time for evacuation of the ambient air to the vacuum level needed for vapor deposition. Moreover, the loading and unloading of a large carrier can require considerable manpower. It is, therefore, desirable to provide an apparatus and process of continuous metallizing which can be accomplished more rapidly and without the need for numerous workers.